Project Fun Buggy Blueprints

I've gotten the letters and I've heard the harassment while on the trail. Yes, I am still building Project Fun Buggy. It's just taking a little while, but here is another installment of the buildup that began over a year ago (Aug. '05). The idea for this tube buggy is an all-terrain vehicle that doesn't have a conventional body but rather is built for optimum fun off road. Though my buildup uses premium parts, it can be duplicated with a junkyard drivetrain on a reasonable budget.

To recap, we started by building front and rear steering axles with Dynatrac Pro-rock Dana 60 centersections, Reid Racing (formerly Dedenbear) end forgings and knuckles, 40-spline Superior shafts, CTM U-joints, and Detroit Lockers (Aug. '05). In addition we used Yukon 5.38 gears with 35-spline pinions, and high-steer arms from OTT. I then went to Scoggin-Dickey and assembled a fuel-injected GM Performance Parts ZZ383 small-block V-8 (Sept. '05). This engine uses an ACCEL DFI fuel-injection system and was dyno'd at just over 400 hp and just shy of 500 lb-ft of torque. Following that, the mil-spec green Mastercraft suspension seats and 17-inch Walker Evans Racing bead-lock wheels were added (Oct. '05). And then there was a lapse until our February 2006 issue where I discussed tubing and showed the difference between HREW, DOM, and chromoly tubing and the fact that I am using about 300 feet of DOM 1 3/4-inch x 0.120 wall tubing for the majority of my project. Then everything fell apart.

From the start of this project I wanted to work with a fabrication shop that could walk me through the steps of the design and buildup. I ended up at Poly Performance in San Luis Obispo, California. Poly has been selling parts for the home tube-buggy builder for five years and has a fabrication shop that does everything from coilover conversions for Jeep TJs to full chassis buildups.

To get everything moving I took my drivetrain parts to Poly and began the extended design, and that is what this month's story is all about. Now I was assuming we would simply park the parts on the shop floor and begin bending tube around it, but boy was I wrong. The team at Poly Performance takes a different approach by measuring every drivetrain component and suspension part, then drawing them up on the computer. This way they can get an initial layout before any tube is bent. It takes longer this way (way longer), and most of us can't duplicate these steps exactly, but similar procedures can be done with pencil and graph paper. Of course I was going crazy trying to get my buggy project moving, but the best advice for a project this big it to have a solid overall plan for the entire vehicle. Though some fabricators can whip a chassis out in their sleep, these drawings made it much easier once the dirty work finally began, and can keep the wasted tube to a minimum. This process also allows many different configurations to be explored before a final design is set.

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The chassis was coming together nicely when I brought up another idea. Here is a pointer for anyone working on a custom buildup; if you keep making changes or "bringing up ideas," your project will take that much longer to get done, and at some point you will need to make a "design freeze," and just get the project moving ahead. Luckily, since we were still at the drawing stage these changes could easily be tried out. My other idea was more a question; could a buggy be built completely out of sheetmetal? Basically build a unibody or monocoque vehicle, but design it to work off road, and be made of thin sheetmetal to keep the weight down. Where some designers would chase me out of the shop at this question, Burroughs rolled it over in his head and offered that we could do certain parts out of thin chromoly sheetmetal with dimpled holes for added rigidity. I liked the idea and soon we had a new substructure drawn where the link suspension will tie in.

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Next month I'll show you how we took these drawings and moved into the fabrication stage of the buildup. Some of you will be able to use these drawings to build a chassis at home, but if fabrication isn't your cup of tea, Poly Performance will be offering a similar chassis for sale that you can install your preferred drivetrain into, or have built as a complete turnkey tube car.